# -*- coding: utf-8 -*-
# 将用户输入百分制的成绩，转换为五分制输出
score = float(input("请输入你的成绩，0-100分："))

if score >= 90 and score <= 100:
    print('A')
elif  score >= 80 and score < 90:
    print('B')
elif score >= 70 and score < 80:
    print('C')
elif score >= 60 and score < 70:
    print('D')
elif score >= 0 and score < 60:
    print('E')
else:
    print('输入错误！请输出0到100之间的数字。')